全文获取类型
收费全文 | 46648篇 |
免费 | 4977篇 |
国内免费 | 1827篇 |
专业分类
耳鼻咽喉 | 364篇 |
儿科学 | 359篇 |
妇产科学 | 418篇 |
基础医学 | 5682篇 |
口腔科学 | 1318篇 |
临床医学 | 4410篇 |
内科学 | 5285篇 |
皮肤病学 | 410篇 |
神经病学 | 3294篇 |
特种医学 | 1546篇 |
外国民族医学 | 1篇 |
外科学 | 4230篇 |
综合类 | 8033篇 |
现状与发展 | 4篇 |
一般理论 | 2篇 |
预防医学 | 7126篇 |
眼科学 | 782篇 |
药学 | 5119篇 |
74篇 | |
中国医学 | 2849篇 |
肿瘤学 | 2146篇 |
出版年
2024年 | 298篇 |
2023年 | 1085篇 |
2022年 | 2124篇 |
2021年 | 2496篇 |
2020年 | 2109篇 |
2019年 | 1660篇 |
2018年 | 1598篇 |
2017年 | 1793篇 |
2016年 | 1667篇 |
2015年 | 1820篇 |
2014年 | 2976篇 |
2013年 | 3408篇 |
2012年 | 2755篇 |
2011年 | 3140篇 |
2010年 | 2417篇 |
2009年 | 2514篇 |
2008年 | 2490篇 |
2007年 | 2481篇 |
2006年 | 2097篇 |
2005年 | 1885篇 |
2004年 | 1499篇 |
2003年 | 1320篇 |
2002年 | 988篇 |
2001年 | 882篇 |
2000年 | 818篇 |
1999年 | 688篇 |
1998年 | 528篇 |
1997年 | 493篇 |
1996年 | 421篇 |
1995年 | 383篇 |
1994年 | 367篇 |
1993年 | 282篇 |
1992年 | 272篇 |
1991年 | 204篇 |
1990年 | 213篇 |
1989年 | 177篇 |
1988年 | 145篇 |
1987年 | 146篇 |
1986年 | 105篇 |
1985年 | 147篇 |
1984年 | 108篇 |
1983年 | 69篇 |
1982年 | 74篇 |
1981年 | 69篇 |
1980年 | 59篇 |
1979年 | 51篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 26篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Depressive Symptoms and Associated Factors in Children With Attention Deficit Hyperactivity Disorder
Nancy LeBlanc PhD RN Diane Morin PhD RN 《Journal of child and adolescent psychiatric nursing》2004,17(2):49-55
PROBLEM: To compare depressive symptoms in children with attention deficit hyperactivity disorder (ADHD) to those in healthy children, and to explore the influence of individual and family factors on level of depression. METHODS: Individual interviews with 68 children, ages 7 to 12 years, in order to complete the Children's Depression Inventory. FINDINGS: Children with ADHD reported significantly more depressive symptoms than did children without ADHD; 14.7% of children with ADHD reached the threshold of a 19 point score, which suggests clinical depression. No significant effects of individual and family factors on level of depression were found. CONCLUSIONS: Children with ADHD are more inclined to experience depressive symptoms than are healthy children. To plan appropriate interventions, nurses evaluating and working with children with ADHD should always consider a possible coexistence of depressive symptoms. 相似文献
62.
立体着床模型--小鼠囊胚与子宫内膜的共培养 总被引:1,自引:0,他引:1
目的:建立小鼠囊胚体外着床的三维模型,为着床机制的研究提供重要工具.方法:将小鼠囊胚与其自身子宫内膜分别共培养在空气、含500,750和950 mL/L O2的混合气体与组织培养液的气液界面上,比较不同O2浓度下小鼠囊胚的贴附率,确定体外共培养的最佳O2浓度;同时将确认有囊胚贴附的子宫内膜取出作HE染色.结果:不同O2浓度下,囊胚的贴附率分别为64.75%,47.86%,42.37%和30.97%,x2检验提示其差异有显著性(x2=28.145,P=0.000);且随着混合气体中O2浓度的逐渐升高,囊胚贴附率呈逐渐降低趋势.因此50 mL/L CO2 950 mL/L空气对囊胚与子宫内膜的共培养是最有利的;同时,囊胚贴附子宫内膜后并无扩展行为而是直接侵入子宫内膜.结论:50 mL/L CO2 950 mL/L空气最有利于囊胚与子宫内膜的共培养;且囊胚贴附子宫内膜后不发生外延生长,而是直接侵入子宫内膜.本实验成功地建立了小鼠囊胚体外着床的三维模型. 相似文献
63.
D M McSherry 《Statistics in medicine》1986,5(5):497-502
The independence Bayesian model has been used widely in computer programs designed to support clinical decision-making. A reasoning strategy has been developed to enable these programs to conduct clinically pertinent dialogue and explain their reasoning. It has been implemented in a program for the diagnosis of acute abdominal pain based on the Bayesian model of de Dombal et al. Several features of the dialogue design have been adopted from artificial intelligence research, including shared initiative and critiquing. The program adopts a flexible goal-driven strategy, attempting to confirm the clinician's diagnosis or rule out the likeliest alternative. Symptoms and signs are selected in order of their expected weights of evidence in favour of the hypothesized disease. 相似文献
64.
Aoyama Takao Yamamoto Koujirou Kotaki Hajime Sawada Yasufumi Iga Tatsuji 《Pharmaceutical research》1997,14(11):1601-1606
Purpose. The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed.
Methods. MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis.
Results. The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 ± 73.8 nM (mean ± SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model.
Conclusions. The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may be useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine. 相似文献
65.
Modulation of cytokine production from an EpiOcular corneal cell culture model in response to Staphylococcus aureus superantigen 总被引:3,自引:0,他引:3
A Thakur PhD A Clegg MSc A Chauhan MSc MDP Willcox PhD 《Clinical & experimental ophthalmology》1997,25(4):43-45
The present study investigated the hypothesis that Staphylococcus aureus enterotoxin B (SEE) produces epithelial cell death and releases inflammatory cytokines that produce stromal infiltration during contact lens induced peripheral ulceration. Epithelial cells were incubated with different doses of SEB for various time periods. Culture supernatants were assayed for cytokines IL- lo, IL-6 and chemotactic agents IL-8 and LTB,. SEE induced the production of IL- I p and IL-8. Epithelial cells exposed for longer periods (48 h) with low concentrations of SEB produced significantly higher levels (N0.02) of IL-Ip and IL-8 (P<0.05) compared t o a 24 h exposure. SEB did not induce the production o f IL-6 and 相似文献
66.
The systolic hump in the aortic blood pressure wave is defined as the aorticresistance component proportional to the aortic
blood flow superimposed on the windkessel component. An electrical analogue comprising a series resistance (aortic resistance)
plus a resistance (peripheral resistance) and capacitance (aortic compliance) in parallel (i.e. windkessel component) is used
for analysis. Curve fitting using the leastsquares method is performed on calculated and measured blood pressure waves from
dogs under haemodynamical conditions induced by infusion of three drugs (noradrenaline, isoproterenol and acetylcholine).
The curve fitting RMS (root mean square) errors are <3% for blood pressure waves and <30% for blood flow waves, with good
agreement between measured and calculated blood flow waveforms. Infusion of noradrenaline and acetylcholine is found to induce
a significant decrease and increase in the aortic resistance, respectively. Although only a small fraction of the blood pressure
wave, the systolic hump has a marked effect on the systolic pressure waveform. 相似文献
67.
熵代表无序的水平,作者使用通气的熵变(ECV)指示肺通气的不均匀性,ECV定义为当前泡潮气量趋近于零时每摩尔被吸入气体从不均匀通气到均匀通气的熵变的极限。本文从熵的基本公式民地出ECV的计算方程。用几个数学模型肺将ECV同其他7个洗出指标进行了比较。8个指标中,只有ECV仅取决于通气分布,其他7个指标不仅取决于通气分布,还同潮气量和死腔的大小有关。这影响了它们评价肺通气不均匀性的效果,ECV的另一 相似文献
68.
Martin Woodhead 《Early child development and care》1990,58(1):129-141
There is now a substantial body of American research evidence demonstrating that early education programmes can have major long term effects right through into adult life. Cost-benefit analysis has enabled the data to be transformed into a compelling case for public financial investment. But insufficient attention has been paid to explaining how a short term preschool programme could have such enduring effects. The effects are best understood by applying a transactional model which shows how processes in the school and community transformed and amplified short term effects into long term outcomes. Adopting a transactional model modifies the messages for policy. The results of evaluations carried out in one society may not apply in another. In some school systems there may be more effective strategies than early education for improving educational prospects. 相似文献
69.
Gene M. Heyman 《Psychopharmacology》1993,112(2-3):259-269
A series of experiments evaluated the determinants of preference for mixtures of ethanol plus sucrose relative to sucrose in rats. One dipper served 10% ethanol mixed with 10% sucrose, and the second dipper served 10% sucrose. Lever presses operated each dipper according to a variable-interval 5-s schedule. In three experiments the subjects were given pre-session meals of sucrose (2.5–20 ml) or sucrose (20 ml) plus chow (5 or 10 g). Pre-session meals decreased responding maintained by sucrose but not responding maintained by ethanol mixture. In two experiments body weight was varied from 85% to 125% of the initial free-feeding values. Increases in body weight, like pre-session meals, decreased responding reinforced by sucrose, but typically did not decrease responding reinforced by ethanol mixture. Throughout most of the study, ethanol consumption remained at about 1.25 ml per half hour session (3–4 g/kg per 30 min). For example, pre-session access to ethanol mixture decreased within-session ethanol consumption, but total consumption, counting both sources, remained about 1.25 ml/session. The within-session patterns of responding also differed. Responding reinforced by ethanol mix decreased as a function of ethanol consumption, whereas responding reinforced by sucrose was relatively constant throughout the session. The simplest explanation of the results is that ethanol's pharmacological consequences regulated preference. 相似文献
70.